RFR(XS) 8190809 JVM crashes while generating appcds for classpath with empty directory entry

[Jiangli Zhou]

Looks good.

Thanks,
Jiangli

> On Dec 1, 2017, at 10:53 AM, Ioi Lam <ioi.lam at oracle.com> wrote:
> 
> Hi
> 
> Please review this very small change. I hope to invoke the trivial rule so that I can push before today's 8PM PDT deadline for JDK 10 integration.
> 
> https://bugs.openjdk.java.net/browse/JDK-8190809
> http://cr.openjdk.java.net/~iklam/jdk10/8190809-cds-crash-empty-cp.v01/
> 
> The crash happened because CDS was trying to use a classpath as a JAR file, before checking it's actually a JAR file.
> 
> I added test case for the use of directories in -cp during CDS dumping, both for empty and non-empty cases.
> 
> I will test with tier1/tier2 testing before pushing.
> 
> Thanks
> - Ioi
> 
> 
> 
> 
> 
> 
> PS: the check for non-emptiness is done in here:
> 
> void ClassLoader::check_shared_classpath(const char *path) {
>   if (strcmp(path, "") == 0) {
>     exit_with_path_failure("Cannot have empty path in archived classpaths", NULL);
>   }
> 
>   struct stat st;
>   if (os::stat(path, &st) == 0) {
>     if ((st.st_mode & S_IFMT) != S_IFREG) { // is not a regular file
>       if (!os::dir_is_empty(path)) {
>         tty->print_cr("Error: non-empty directory '%s'", path);
>         exit_with_path_failure("CDS allows only empty directories in archived classpaths", NULL);
>       }
>     }
>   }
> }
> 
>